rustc: Introduce a lang_items pass, part of coherence and operator overloading.

This will also help us remove kinds.

src/rustc/middle/lang_items.rs

@@ -0,0 +1,209 @@
+// Detecting language items.
+//
+// Language items are items that represent concepts intrinsic to the language
+// itself. Examples are:
+//
+// * Traits that specify "kinds"; e.g. "const", "copy", "send".
+//
+// * Traits that represent operators; e.g. "add", "sub", "index".
+//
+// * Functions called by the compiler itself.
+
+import driver::session::session;
+import metadata::csearch::{each_path, get_item_attrs};
+import metadata::cstore::{iter_crate_data};
+import metadata::decoder::{dl_def, dl_field, dl_impl};
+import syntax::ast::{crate, def_id, def_ty, lit_str, meta_item, meta_list};
+import syntax::ast::{meta_name_value, meta_word};
+import syntax::ast_util::{local_def};
+import syntax::visit::{default_simple_visitor, mk_simple_visitor};
+import syntax::visit::{visit_crate, visit_item};
+
+import std::map::{hashmap, str_hash};
+import str_eq = str::eq;
+
+class LanguageItems {
+    let mut const_trait: option<def_id>;
+    let mut copy_trait: option<def_id>;
+    let mut send_trait: option<def_id>;
+    let mut owned_trait: option<def_id>;
+
+    let mut add_trait: option<def_id>;
+    let mut sub_trait: option<def_id>;
+    let mut mul_trait: option<def_id>;
+    let mut div_trait: option<def_id>;
+    let mut modulo_trait: option<def_id>;
+    let mut neg_trait: option<def_id>;
+    let mut bitops_trait: option<def_id>;
+    let mut index_trait: option<def_id>;
+
+    new() {
+        self.const_trait = none;
+        self.copy_trait = none;
+        self.send_trait = none;
+        self.owned_trait = none;
+
+        self.add_trait = none;
+        self.sub_trait = none;
+        self.mul_trait = none;
+        self.div_trait = none;
+        self.modulo_trait = none;
+        self.neg_trait = none;
+        self.bitops_trait = none;
+        self.index_trait = none;
+    }
+}
+
+class LanguageItemCollector {
+    let items: LanguageItems;
+
+    let crate: @crate;
+    let session: session;
+
+    let item_refs: hashmap<~str,&mut option<def_id>>;
+
+    new(crate: @crate, session: session) {
+        self.crate = crate;
+        self.session = session;
+
+        self.items = LanguageItems();
+
+        self.item_refs = str_hash();
+    }
+
+    // XXX: Needed to work around an issue with constructors.
+    fn init() {
+        self.item_refs.insert(~"const", &mut self.items.const_trait);
+        self.item_refs.insert(~"copy", &mut self.items.copy_trait);
+        self.item_refs.insert(~"send", &mut self.items.send_trait);
+        self.item_refs.insert(~"owned", &mut self.items.owned_trait);
+
+        self.item_refs.insert(~"add", &mut self.items.add_trait);
+        self.item_refs.insert(~"sub", &mut self.items.sub_trait);
+        self.item_refs.insert(~"mul", &mut self.items.mul_trait);
+        self.item_refs.insert(~"div", &mut self.items.div_trait);
+        self.item_refs.insert(~"modulo", &mut self.items.modulo_trait);
+        self.item_refs.insert(~"neg", &mut self.items.neg_trait);
+        self.item_refs.insert(~"bitops", &mut self.items.bitops_trait);
+        self.item_refs.insert(~"index", &mut self.items.index_trait);
+    }
+
+    fn match_and_collect_meta_item(item_def_id: def_id,
+                                   meta_item: meta_item) {
+
+        alt meta_item.node {
+            meta_name_value(key, literal) => {
+                alt literal.node {
+                    lit_str(value) => {
+                        self.match_and_collect_item(item_def_id,
+                                                    *key,
+                                                    *value);
+                    }
+                    _ => {
+                        // Skip.
+                    }
+                }
+            }
+            meta_word(*) | meta_list(*) {
+                // Skip.
+            }
+        }
+    }
+
+    fn match_and_collect_item(item_def_id: def_id, key: ~str, value: ~str) {
+        if !str_eq(key, ~"lang") {
+            ret;    // Didn't match.
+        }
+
+        alt self.item_refs.find(value) {
+            none => {
+                // Didn't match.
+            }
+            some(item_ref) => {
+                // Check for duplicates.
+                alt copy *item_ref {
+                    some(original_def_id)
+                            if original_def_id != item_def_id => {
+
+                        self.session.warn(#fmt("duplicate entry for `%s`",
+                                               value));
+                    }
+                    some(_) | none => {
+                        // OK.
+                    }
+                }
+
+                // Matched.
+                *item_ref = some(item_def_id);
+            }
+        }
+    }
+
+    fn collect_local_language_items() {
+        let this = unsafe { ptr::addr_of(self) };
+        visit_crate(*self.crate, (), mk_simple_visitor(@{
+            visit_item: |item| {
+                for item.attrs.each |attribute| {
+                    unsafe {
+                        (*this).match_and_collect_meta_item(local_def(item
+                                                                      .id),
+                                                            attribute.node
+                                                                     .value);
+                    }
+                }
+            }
+            with *default_simple_visitor()
+        }));
+    }
+
+    fn collect_external_language_items() {
+        let crate_store = self.session.cstore;
+        do iter_crate_data(crate_store) |crate_number, _crate_metadata| {
+            for each_path(crate_store, crate_number) |path_entry| {
+                let def_id;
+                alt path_entry.def_like {
+                    dl_def(def_ty(did)) => {
+                        def_id = did;
+                    }
+                    dl_def(_) | dl_impl(_) | dl_field {
+                        // Skip this.
+                        again;
+                    }
+                }
+
+                do get_item_attrs(crate_store, def_id) |meta_items| {
+                    for meta_items.each |meta_item| {
+                        self.match_and_collect_meta_item(def_id, *meta_item);
+                    }
+                }
+            }
+        }
+    }
+
+    fn check_completeness() {
+        for self.item_refs.each |key, item_ref| {
+            alt copy *item_ref {
+                none => {
+                    self.session.warn(#fmt("no item found for `%s`", key));
+                }
+                some(did) => {
+                    // OK.
+                }
+            }
+        }
+    }
+
+    fn collect() {
+        self.init();
+        self.collect_local_language_items();
+        self.collect_external_language_items();
+        self.check_completeness();
+    }
+}
+
+fn collect_language_items(crate: @crate, session: session) -> LanguageItems {
+    let collector = LanguageItemCollector(crate, session);
+    collector.collect();
+    copy collector.items
+}
+